Deposition of thin films on a substrate surface is an important process in a variety of industries including semiconductor processing, diffusion barrier coatings and dielectrics for magnetic read/write heads. In the semiconductor industry, in particular, miniaturization requires atomic level control of thin film deposition to produce conformal coatings on high aspect structures.
One method for deposition of thin films is atomic layer deposition (ALD). Most ALD processes are based on binary reaction sequences, where each of the two surface reactions occurs sequentially. Because the surface reactions are sequential, the two gas phase reactants are not in contact, and possible gas phase reactions that may form and deposit particles are limited. While ALD tends to result in more conformal films than traditional chemical vapor deposition (CVD), prior art processes for ALD have been most effective for deposition of metal oxide and metal nitride films. Although a few processes have been developed that are effective for deposition of elemental ruthenium and other late transition metals, in general ALD processes for deposition of pure metal have not been sufficiently successful to be adopted commercially.
Pure metal films of aluminum have many applications in the integrated circuit manufacturing process. Aluminum precursors tend to decompose or isomerize inside the ampoules used as reactive gas sources, leading to process drift. Therefore, there is a need in the art for classes of compounds that are less likely to decompose or isomerize in the ampoules, and are reactive for CVD and ALD processes.